Uhf rfid internal antenna for handheld terminals

Abstract

A microstrip antenna, such as an internal patch antenna with circular polarization diversity, configured for at least one of transmission or reception of electromagnetic waves, such as in the UHF spectrum, with respect to a surrounding environment. The antenna comprises: an antenna element isolated from an electrical ground of the antenna and configured for operating as a radiating surface for the electromagnetic waves with respect to the surrounding environment; a transmission line having a pair of electrical conductors such that a first conductor of the pair of electrical conductors is connected to the antenna element and a second conductor of the pair of electrical conductors is configured for coupling to the electrical ground, such that the transmission line is configured to conduct current flow for at least one of towards the antenna element for transmission of the electromagnetic waves from the antenna element or away from the antenna element as a result of reception of the electromagnetic waves by the antenna element; and a composite substrate having a selected dielectric constant including a plurality of individual dielectric material layers in a stacked layer arrangement, such that the composite substrate is positioned between the antenna element and the electrical ground and the antenna element is attached to a first surface of the composite substrate. Further, an optional ground element can be attached to the other side of the composite substrate and the tuning of the antenna can be dual band in the UHF or higher frequency spectra.

1 . A microstrip antenna configured for at least one of transmission or reception of electromagnetic waves with respect to a surrounding environment, the antenna comprising:
 an antenna element isolated from an electrical ground of the antenna and configured for operating as a radiating surface for the electromagnetic waves with respect to the surrounding environment;   a transmission line having a pair of electrical conductors such that a first conductor of the pair of electrical conductors is connected to the antenna element and a second conductor of the pair of electrical conductors is configured for coupling to the electrical ground, such that the transmission line is configured to conduct current flow for at least one of towards the antenna element for transmission of the electromagnetic waves from the antenna element or away from the antenna element as a result of reception of the electromagnetic waves by the antenna element; and   a composite substrate having a selected dielectric constant including a plurality of individual dielectric material layers in a stacked layer arrangement, such that the composite substrate is positioned between the antenna element and the electrical ground and the antenna element is attached to a first surface of the composite substrate.   
     
     
         2 . The antenna of  claim 1  further comprising each pair of the individual dielectric material layers being bonded to one another by a respective interposing bonding layer. 
     
     
         3 . The antenna of  claim 2 , wherein the bonding layer is a doubled sided adhesive tape. 
     
     
         4 . The antenna of  claim 2 , wherein the antenna element is a metallic patch selected from the group comprising: a two dimensional metallic sheet; and one or more metallic traces. 
     
     
         5 . The antenna of  claim 4 , wherein the metallic sheet is a rectangular shape. 
     
     
         6 . The antenna of  claim 2  further comprising a grounding element attached to a second surface of the composite substrate, such that the first and second surfaces are in an opposed spatial relationship to one another. 
     
     
         7 . The antenna of  claim 6 , wherein the second conductor of the pair of electrical conductors is connected to the grounding element and the grounding element is configured for coupling to the electrical ground. 
     
     
         8 . The antenna of  claim 6 , wherein the ground element is a metallic sheet. 
     
     
         9 . The antenna of  claim 8 , wherein the metallic sheet is in the shape of a rectangle. 
     
     
         10 . The antenna of  claim 9 , wherein the electrical ground is provided by a handheld terminal and the current flow is provided by a power source of the handheld terminal for the transmission of the electromagnetic waves. 
     
     
         11 . The antenna of  claim 2  further comprising the antenna configured as circular polarization diversity. 
     
     
         12 . The antenna of  claim 11  further comprising a pair of orthogonal slots in the antenna element for facilitating tuning of a wavelength band of the antenna. 
     
     
         13 . The antenna of  claim 12 , wherein the configuration of the pair of orthogonal slots provides for two different wavelength bands, such that the antenna is a dual band antenna. 
     
     
         14 . The antenna of  claim 11 , wherein the effective dielectric constant of the composite substrate is greater than 9 and the thickness of the stacked layer arrangement is approximately ½ inch. 
     
     
         15 . The antenna of  claim 14 , wherein the shape of the antenna is a rectangular shape and is configured for positioning as an internal antenna in a housing of a handheld device. 
     
     
         16 . The antenna of  claim 15 , wherein a number of the plurality of individual dielectric material layers is 4. 
     
     
         17 . An antenna apparatus comprising: an antenna element configured to be isolated from an electrical ground of the antenna; a transmission line having a pair of electrical conductors such that a first conductor of the pair of electrical conductors is connected to the antenna element and a second conductor of the pair of electrical conductors is configured for coupling to the electrical ground; and a composite substrate having a selected relative static permittivity including a plurality of individual relative static permittivity material layers in a stacked layer arrangement, such that the composite substrate is positioned between the antenna element and the electrical ground and the antenna element is attached to a first surface of the composite substrate. 
     
     
         18 . The antenna apparatus of  claim 17 , wherein the antenna element is a configured as a radiating surface for electromagnetic waves in the UHF spectra. 
     
     
         19 . A mobile computing device containing the antenna of  claim 17  associated with a first transceiver, receiver or transmitter and containing or supporting at least one additional antenna connected to at least one additional transmitter, receiver or transceiver, such that the antenna and the additional antenna are configured for simultaneous operation.